The present invention generally relates to a cargo vehicle, and to a cargo-work controlling apparatus which is adapted to retain the posture of a container on loading the detachable container on the body of the vehicle or unloading it from the body. More particularly, the present invention relates to a cargo-work vehicle, wherein support arms having container supports are provided for front and rear pivotal movements, an auxiliary arm which is adapted to always retain the container in a horizontal condition is provided for front and rear pivotal movements through connection with the container on the front portion of the vehicle body.
Some vehicles carrying the containers have a cargo-work apparatus, which is adapted to load the container on the vehicle body, unload it or replace it. It is necessary to support the container for loading or unloading the container by this apparatus. Thus, support shafts are projected to right and left of the container. To receive the support shafts, the cargo-work apparatus has a lift arm which is formed with the support unit. The lift arm is supported on the body of the vehicle for forward and rearward rotation by a lift cylinder to be operated through hydraulic power or the like. One embodiment wherein this type of lift arm is employed is described in Japanese Patent Publication Tokukosho No. 31-3170. The container is adapted to be supported by the lift arm only through a pair of opposite support shafts. The mounting positions for the support shafts are considered higher than the center of the gravity so that the container may not be tilted during the cargo-work operation.
In order to load and unload the container, the arm main body is branched into a fork shape in the lift arm which is adapted to rotate forwardly and rearwardly. The root forms the supports for the container. The support shafts are mounted on the supports. As a result, the support shafts may rotatably slide by the supports while the lift arm is rotating forwardly and rearwardly, so that the posture of the container may be maintained. However, when the goods within the container, the accommodation position for the received or the weight distribution is not balanced, the container is adapted to be supported in the inclined posture from the beginning. When the cargo is loaded or unloaded in such a posture as described hereinabove, the container is oscillated and becomes unstable. The accommodated may collapse as the case may be. The goods may fall or fly away in the case of the container with no cover or ceiling being provided thereon.
In order to improve the disadvantages, one portion of the container to supported is necessary to be auxiliarily supported, when the lift arm is rotated forwardly, rearwardly, to prevent the posture of the container from being varied. In order to realize it, the construction is adopted wherein the auxiliary arm which rotates forwardly, rearwardly is provided on the body of the vehicle for the operative cooperation with the forward, rearward rotation of the lift arm through the container. However, as it is necessary for the auxiliary arm to be kept capable to singly rotate forwardly, rearwardly, the cylinder for the exclusive use of the auxiliary arm.
When the container is supported in such arrangements, ill influences are provided that the operation of one cylinder obstructs the operation of the other cylinder, which is different from the one cylinder is stroke amount, stroke speed. Accordingly, a controlling apparatus is desired which is capable of selectively switching the invertedly operational condition and the independently operational condition of the auxiliary cylinder in accordance with a case where the auxiliary arm is operatively cooperated in concert with the forward, rearward rotation of the lift arm or a case where the auxiliary arm is not operatively cooperated.